"Both of those sites were chosen because of the impact the property could have on downtown if developed properly," said Lisa Flint, a spokeswoman for River City Co..

The 700 block has been an especially sore subject for city dwellers in recent years.

Frequently cited as the cavity in Chattanooga's smile, the 24,000-square-foot property was the centerpiece of a years-long legal battle that finally ended with the land reverting to its former owner, nonprofit developer River City Co.

The prime chunk of real estate was to become a $16 million condo project called Mayfair on Market, but former developer Trey Stanley failed to build anything after a decade of ownership.

"Based on interest we have been receiving from the development community, we feel now is the time to focus on finding the highest and best use of these parcels to take our downtown to the next level," said Jim Williamson, vice president of planning and development at River City Co.

Stanley's Trafalger Development Corp. initially purchased the land from River City Co. in 2000, finally razed the buildings in 2008, and spent $2.2 million on demolition and asbestos abatement, he has said.

But when the Chattanooga Housing Authority diverted $1.2 million in federal dollars it had committed to the project into its general fund, Stanley halted the project and ultimately lost control to River City Co. after a lawsuit.

Since River City Co. reclaimed the land and cleaned up the property, it has been approached by more than a dozen developers, said Kim White, president and CEO of the nonprofit developer.

"What we'd like to see, and we're going to be pretty specific about it, is that it must have retail frontage, it's got to have some type of parking, and we'd love to see some connectivity to Cherry Street," White said.

The Urban Design Challenge envisioned the site with a grocery store and a multistory stack of apartments, stores and restaurants.

In its request, River City mandates a mix of retail, residential, entertainment and "green" elements.

On its 30,000-square-foot Broad Street property -- which is currently a parking lot -- the developer is thinking of a five- to six-story hotel, White said.

Whatever happens, "we would definitely want to do something retail-oriented on the first floor," she said.

"On both projects, having something retail on that first floor is imperative," White said.

A recent proposal for the Fourth Street corridor that includes the Broad Street site showed a mix of hotels, streetscape enhancements and a vast expansion to the Creative Discover museum.

Proposals are due by May 28, 2012. River City Co. expects construction to begin by mid-2013.